!7

p-exp {
  byte[] data = loadBinaryFile(userDir(".mozilla/firefox/peppermint.default/sessionstore-backups/recovery.jsonlz4"));
  print("Have data: " + l(data));
  if (empty(data)) ret;
  
  print(bytesToHex(subByteArray(data, 0, 16)));
  
  int lDecompressed = intFromBytes_littleEndian(data, 8);
  print("lDecompressed=" + lDecompressed);
  
  // see http://fastcompression.blogspot.com/2011/05/lz4-explained.html
  
  int i = 12, n = l(data), iOut = 0;
  byte[] out = new byte[lDecompressed];
  while (i < n) {
    int lLiteral = (data[i] >> 4) & 0x0F;
    int lMatches = (data[i] & 0x0F)+4;
    i++;
    print("lLiteral=" + lLiteral + ", lMatches=" + lMatches);
    if (lLiteral == 15) {
      int more;
      do {
        more = data[i++] & 0xFF;
        lLiteral += more;
        print("lLiteral >> " + lLiteral);
      } while (more == 255);
    }
    print("Have literal: " + quote(fromUtf8_subArray(data, i, lLiteral)));
    arraycopy(data, i, out, iOut, lLiteral);
    iOut += lLiteral;
    i += lLiteral;
    if (i >= n) break;
    int offset = data[i] & 0xFF | (data[i+1] & 0xFF) << 8;
    print("offset=" + offset);
    i += 2;
    if (offset == 0) break with print("bad offset");
    if (lMatches == 19) {
      int more;
      do {
        more = data[i++] & 0xFF;
        lMatches += more;
        print("lMatches >> " + lLiteral);
      } while (more == 255);
    }
    int j = lMatches;
    while (j-- > 0) {
      out[iOut] = out[iOut-offset];
      iOut++;
    }
    print("Got match: " + quote(fromUtf8_subArray(out, iOut-lMatches, lMatches)));
    //break;
  }
  saveProgramTextFile("uncompressed.json", fromUtf8(out));
}